Oxacillin Sodium
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4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid,3,3-dimethyl-6-[[(5-methyl-3-phenyl-4-isoxazolyl)carbonyl]amino]-7-oxo-,monosodium salt,monohydrate,[2S-(2a,5a,6b)]-.
Monosodium (2S,5R,6R)-3,3-dimethyl-6-(5-methyl-3-phenyl-4-isoxazolecarboxamido)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate monohydrate [7240-38-2].
Anhydrous 423.43 [1173-88-2].
»Oxacillin Sodium contains the equivalent of not less than 815µg and not more than 950µg of oxacillin (C19H19N3O5S)per mg.
Packaging and storage—
Preserve in tight containers,at controlled room temperature.
Labeling—
Where it is intended for use in preparing injectable dosage forms,the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
Identification—
A:
The chromatogram of the Assay preparationobtained as directed in the Assayexhibits a major peak for oxacillin,the retention time of which corresponds to that exhibited in the chromatogram of the Standard preparationobtained as directed in the Assay.
B:
It responds to the tests for Sodium á191ñ.
Crystallinity á695ñ:
meets the requirements.
pHá791ñ:
between 4.5and 7.5,in a solution containing 30mg per mL.
Water,Method Iá921ñ:
between 3.5%and 5.0%.
Other requirements—
Where the label states that Oxacillin Sodium is sterile,it meets the requirements for Sterilityand Bacterial endotoxinsunder Oxacillin for Injection.Where the label states that Oxacillin Sodium must be subjected to further processing during the preparation of injectable dosage forms,it meets the requirements for Bacterial endotoxinsunder Oxacillin for Injection.
Assay—
Mobile phase—
Dissolve 1.9g of monobasic potassium phosphate in 700mLof water.Add 300mLof acetonitrile and 100mLof methanol,and mix.Filter this solution through a 0.5-µm or finer porosity filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Standard preparation—
Dissolve an accurately weighed quantity of USP Oxacillin Sodium RSin water to obtain a solution having a known concentration of about 0.11mg per mL.[NOTE—Use this Standard preparation on the day prepared.]
Assay preparation—
Transfer about 115mg of Oxacillin Sodium,accurately weighed,to a 200-mLvolumetric flask,add water to volume,and mix.Stir with the aid of a magnetic stirrer for 5minutes to ensure dissolution of the specimen.Transfer 10.0mLof this solution to a 50-mLvolumetric flask,dilute with water to volume,and mix.[NOTE—Use this Assay preparation on the day prepared.]
Chromatographic system
(see Chromatography á621ñ)—The liquid chromatograph is equipped with a 225-nm detector and a 4-mm ×30-cm column that contains packing L11.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the responses as directed for Procedure:the column efficiency is not less than 2000theoretical plates,the tailing factor is not more than 1.6,and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
[NOTE—Use peak areas where peak responses are indicated.]Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in µg,of oxacillin (C19H19N3O5S)in each mg of the Oxacillin Sodium taken by the formula:
1000(CE/W)(rU/rS),
in which Cis the concentration,in mg per mL,of USP Oxacillin Sodium RSin the Standard preparation;Eis the oxacillin equivalent,in µg per mg,of USP Oxacillin Sodium RS;Wis the weight,in mg,of the portion of Oxacillin Sodium taken;and rUand rSare the oxacillin peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information—
Staff Liaison:William W.Wright,Ph.D.,Scientific Fellow
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1424
Phone Number:1-301-816-8335